Irish Surnames

The Library at Trinity College, Dublin
The Library at Trinity College, Dublin

Irish surnames are rich in history and cultural significance, reflecting the country’s long and complex past. From ancient Gaelic clans to Viking invaders, from English colonization to the Great Famine, the evolution of Irish surnames is intertwined with the story of Ireland itself.

Despite the challenges of migration and assimilation, many Irish surnames have survived and continue to thrive around the world, serving as a testament to the enduring legacy of the Irish people. In this article, we will explore the origins and meanings of some of the most common Irish surnames, and the fascinating stories behind them.

The Most Common Irish Surnames (1890)

For the data we looked at the most numerous surnames in Ireland in 1890, according to a study by Robert Matheson who was then Registrar-General of Ireland. From what we have seen, most online lists of the most common Irish surnames can be traced back to this as the original source.

There is a great research done by the Irish-Genealogy-Toolkit here. This research also looks at the Griffith’s Valuation, which was a survey largely in the 1850s.

  1. Murphy
  • 13,539 Murphy households recorded in mid-19th century
  • Cork, Wexford, and Kilkenny were the most prevalent areas
  • Total population estimated at 62,600 in 1890
  • Derived from O’Murchadha and MacMurchadha meaning ‘sea warrior’
  1. Kelly
  • 11,518 Kelly households recorded in mid-19th century
  • Galway, Roscommon, and Mayo were the most prevalent areas
  • Total population estimated at 55,900 in 1890
  • Meaning is uncertain, may have come from ‘strife’
  • Still commonly used as a first name
  1. O’Sullivan
  • 8,000 O’Sullivan households recorded in mid-19th century
  • Nearly three-quarters were in Cork or Kerry
  • 90% of O’Sullivans estimated to be in Munster in 1890
  • Derived from ‘hawk-eyed’ or ‘one-eyed’
  1. Walsh
  • 9,843 households named Walsh/e, Welsh, Welch or Brannagh recorded in Griffith’s Valuation (1847-1864)
  • Largest clusters found in counties Kilkenny (1,420), Cork (1,357) and Mayo (1,092)
  • Name was most common in Galway, Dublin, Wexford, Cork and Mayo
  • Numbers were lowest in Ulster
  • Originally Breatnach, meaning ‘from Wales’
  • Name is usually pronounced ‘Welsh’ in Munster and Connacht
  1. Smith
  • Scattered across the island, most numerous in Counties Cavan (1,074), Down (635) and Meath (578)
  • More than half the Smiths were in Ulster, and more than one quarter in Leinster
  • Meaning may not suggest English ancestry as many MacGowans had their name translated to Smith
  1. O’Brien
  • One of the great Irish surnames centred on Munster
  • Largest concentrations of O’Brien households were found in Cos Limerick (725), Claire (511), Tipperary (455) and Cork (418)
  • Without the ‘O’ prefix, the name was most common in Cork (806) and Tipperary (628)
  • Smallest numbers in counties Wicklow, Carlow and Kilkenny
  • In Irish, O’Briain means ‘descendant of Brian (Boru)’, the name means ‘exalted one’ or ’eminence’
  • 490 O’Brien registered births in 1890, all were in Munster or Dublin
  • Without the ‘O’ prefix, there were around 80 births registered, in counties Meath, Kilkenny, Wicklow and Wexford
  1. Byrne
  • By far the most prevalent county for Byrne households in the mid-19th century was Wicklow where it was recorded 1203 times
  • The neighbouring counties of Dublin (893), Carlow (572) and Wexford (534) were the next largest concentrations
  • Smallest numbers were found in Derry (9)
  • Leinster was the great stronghold of this name, with five times more Byrnes than the other three provinces combined
  • More than half (301) of the 568 Byrne births in 1890 were in Co. Dublin; 87 were in Co Wicklow
  • O’Broin, meaning raven, can be traced back to Bran, the son of an 11th-century king of Leinster

8. Ryan

  • 8,871 Ryan households recorded in Griffith’s Valuation
  • Nearly half (4,090) of these households were in Tipperary
  • In 1890, more than half of all Ryan births were in Munster, especially counties Tipperary and Limerick
  • O’Mulriain was the Old Irish spelling of the name, meaning ‘little king’
  • O’Riain is the modern Irish spelling, and the sept of this name was from the Tipperary/Limerick borders
  • The name means ‘little king’

9. O’Connor

  • Connor was the most numerous variant of the name in the mid-19th century
  • 5,377 households using the singular form of Connor were mainly found in Kerry and Cork
  • 1,749 households used the plural form Connors, especially in Wexford and Waterford
  • Only 841 households used the name O’Connor, mainly in Munster
  • In 1890, 80% of Connor/O’Connor births were in Kerry, Cork, Limerick, Dublin, Clare, and Galway
  • O’Connor means ‘lover of hounds’

10. O’Neill

  • The Neills and O’Neills were fairly evenly split with 2,578 and 2,720 households respectively
  • Just 537 of the former and 1,412 of the latter were in the six counties that now make up Northern Ireland
  • In 1890, there were 407 O’Neill births covering nearly all counties, but more than half were in Dublin, Antrim, Cork, and Tyrone
  • Only 28 O’Neill births were in Connacht
  • O’Neill means descendant of Niall, a first name which means ‘vehement’

11. O’Reilly

  • Griffith’s Valuation shows that the greatest concentration of Reilly households was in County Cavan (1,759)
  • Reilly households outnumbered O’Reillys nearly 20-1
  • In 1890, County Cavan remained the stronghold of Reillys with 137 births registered
  • But there were 319 births elsewhere, including 93 in Dublin and 78 in Longford
  • Only 10% of Reillys used the O’ prefix at this time
  • The name comes from raghallaigh, possibly meaning ‘sociable tribe or group’
  • By the dawn of the 21st century, almost 60% of Reillys used the O’ prefix

12. Doyle

  • Griffith’s Valuation found there were 4,634 Doyle households recorded across Ireland
  • More than half were in Wexford (1,169), Wicklow (556), Carlow (393), and Dublin (330)
  • Of the 360-odd Doyle birth registrations in 1890, three-quarters were in Counties Dublin (162) and Wexford (102)
  • Other ‘big’ Doyle counties were Kildare, Carlow, and Wicklow
  • The name comes from the Irish for ‘dark stranger,’ possibly meaning Vikings, and is not believed to have any Celtic connections.

Most Common Irish Surnames Today

To get the most up to date data, we looked at Central Statistics Office data from births in 2021. These are the most common Irish Surnames from babies born in Ireland today:

  1. Murphy
  2. Kelly
  3. Ryan
  4. Walsh
  5. Byrne
  6. O’Brien
  7. O’Connor
  8. O’Sullivan
  9. McCarthy
  10. Doyle

Written / Updated